Fuel filler pipes face many technical challenges such as tougher regulations on evaporative gas and satisfactory compatibility with a lightweight material and biofuel according to CO2 regulations. Plastic as a material of fuel filler pipes is suitable as a lightweight material, but barrier properties against alcoholic gas according to a change in a composition of gasoline fuel due to addition of bio-ethanol are problematic. Since component materials of conventional fuel tank injection parts include nylon and rubber, the materials have superior barrier properties against conventional gasoline, but weak barrier properties against alcohol.
In addition, there is a need for development of materials having superior barrier properties due to strengthening of laws and regulations on evaporative gas. The permissible level of evaporative gas is 10 mg or less (F/Neck Ass'y 30 mg) with respect to E0 in Korea, 100 mg (EURO IV) with respect to E10 in Europe, and 2.5 mg (EPA Regulation Level III) with respect to E10 in North America.
Meanwhile, since high density polyethylene (HDPE) conventionally used as a resin for blow molding has a fuel barrier property of 68 g·mm/m2/day which is not excellent, HDPE may be used as a part of a multilayered structure with an ethylene vinyl alcohol copolymer (EVOH). However, expensive multiple extruders should be used to form a multilayered structure, and a satisfactory design for blow extrudability is required.
Accordingly, nylon-based resins having superior barrier properties may be used. However, polyamide 6 among nylon-based resins has superior barrier properties against gasoline but unsatisfactory low-temperature impact properties.
Korean Patent No. 1002050 discloses a multilayered article having barrier properties including a nanoscale composite blend layer having barrier properties where a polyolefin resin is dispersed in a continuous phase of a nanoscale composite of a polyolefin layer and a resin having barrier properties/layered clay compound. However, a specific screw for forming a polyamide dispersion layer in a polyethylene resin is necessary and it is difficult to efficiently control morphology upon blow molding.
In addition, Korean Patent Application Pub. No. 2011-0012430 discloses a resin selected from the group consisting of polyamide resin, polyolefin resin, polyolefin-based thermoplastic elastic body resin, and the like, and a conductive polyamide complex composition including carbon black and carbon nanotubes. However, it is very difficult to control a polyamide dispersion layer in blow molding, and there are disadvantages such as decreased gas and gasoline blocking due to the addition of a large amount of a compatibilizer to a polyolefin resin and difficulty in morphology control.
In addition, US Patent Application Pub. No. 2011-0217495 discloses a thermoplastic molding material composed of polyamide-6, a nanofiller, a fibrous filler, an impact regulator and a blow-molding material including polyamide-66. However, impact resistance is decreased and elongation stress increases due to the addition of inorganic material (fibrous filler), and thus, elongation properties are decreased, whereby blow moldability becomes poor.
In addition, Korean Patent Application Pub. No. 2006-0120548 discloses an MXD-6 nano resin composition having superior gas barrier properties prepared by blending an immobilized inorganic layered clay compound and m-xylenediamine (MXD-6) as a crystalline polyamide resin. When an MXD-6 nano blend is prepared, preparation costs increase and heat stability of a layered clay compound is low, whereby molding is difficult due to gas generation, etc. upon blow molding. In addition, it is difficult to secure impact resistance required in components of an injection part of a fuel tank using only an MXD-6 or MXD-6 nano blend composition.
Therefore, there is a need for development of a material which may be easily blow-molded, may enhance impact resistance, tensile strength and gas barrier properties, and may be applied to components of an injection part of a fuel tank.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.